Unexpected null argument: compareByName(@org.checkerframework.common.aliasing.qual.MaybeAliased, null)

[perceptron8]

Since JDK 22 , the implementation of TypeMirror provides access to annotations for types loaded from bytecode (see JDK-8323094). Type annotations are now visible to javac plugins across compilation boundaries (see JDK-8323093)

---

Reproducer:

$ git clone https://github.com/perceptron8/checker-framework_JDK-8323094
$ cd checker-framework_JDK-8323094/

JDK 21 compilation:

$ export JAVA_HOME=/usr/lib/jvm/java-21-openjdk-amd64/
$ mvn clean verify
[INFO] BUILD SUCCESS

JDK 25 compilation:

$ export JAVA_HOME=/usr/lib/jvm/java-25-openjdk-amd64/
$ mvn clean verify
[INFO] BUILD FAILURE
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.14.1:testCompile (default-testCompile) on project checker-framework_JDK-8323094: Compilation failure
[ERROR] error: Unexpected null argument:  compareByName(@org.checkerframework.common.aliasing.qual.MaybeAliased, null)

With manual javac call, I was able to get a little bit more:

error: Unexpected null argument:  compareByName(@org.checkerframework.common.aliasing.qual.MaybeAliased, null)
  ; The Checker Framework crashed.  Please report the crash.  Version: Checker Framework 3.51.1. 
  Compilation unit: ./src/test/java/MyTest.java
  Last visited tree at line 3 column 17:
                W.wrap(C.create());
  Exception: java.lang.Throwable; java.lang.Throwable
        at org.checkerframework.javacutil.BugInCF.<init>(BugInCF.java:38)
        at org.checkerframework.javacutil.AnnotationUtils.compareByName(AnnotationUtils.java:157)
        at org.checkerframework.javacutil.AnnotationUtils.areSameByName(AnnotationUtils.java:192)
        at org.checkerframework.javacutil.AnnotationUtils.getSameByName(AnnotationUtils.java:383)
        at org.checkerframework.javacutil.AnnotationUtils.containsSameByName(AnnotationUtils.java:368)
        at org.checkerframework.framework.type.AnnotatedTypeMirror.hasExplicitAnnotation(AnnotatedTypeMirror.java:623)

---

("src/main/java/" and "src/test/java/" are compiled separately; bug appears during the latter - that's why I think it is related to JDK-8323094).

---

AnnotationTypeMirror.hasExplicitAnnotation(Class<? extends Annotation>) is currently implemented like so:

checker-framework/framework/src/main/java/org/checkerframework/framework/type/AnnotatedTypeMirror.java

Lines 622 to 624 in f17fd42

	public boolean hasExplicitAnnotation(Class<? extends Annotation> a) {
	return AnnotationUtils.containsSameByName(getExplicitAnnotations(), getPrimaryAnnotation(a));
	}

1. getExplicitAnnotations():

   • on JDK 21 returns [],
   • on JDK 22+ returns [@MaybeAliased, @MaybeLeaked].

2. getPrimaryAnnotation(a)

   • returns null regardless of JDK version.

When collection returned by 1. has no elements, null returned by 2. is harmless. When it has some elements, AnnotationUtils.compareByName is called with a2 being null which leads to BugInCF.

[msugakov]

Also affected by this. Is there any workaround, like making getExplicitAnnotations() return no elements?

[perceptron8]

IMO it would be better to simply check if getPrimaryAnnotation(a) returned null (and, if so, return false). getExplicitAnnotations() seems to be working just fine.

[mernst]

@perceptron8 Thank you for the bug report, and sorry for taking so long to address it. Your suggestion for a fix was a good one.